#!/usr/bin/env python3

"""
Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.

Symbol     Value
I            1
V            5
X           10
L           50
C           100
D           500
M           1000

For example, two is written as II in Roman numeral, just two one's added together. Twelve is written as XII,
which is simply x + II. The number twenty seven is written as XXVII, which is XX + V + II.

Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is 
not IIII. Instead, the number four is written as IV. Because the one is before the five we subtract it making 
four. The same principle applies to the number nine, which is written as IX. There are six instances where 
subtraction is used:
- I can be placed before V(5) and X(10) to make 4 and 9.
- X can be placed before L(50) and C(100) to make 40 and 90.
- C can be placed before D(500) and M(1000) to make 400 and 900.

Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999.
"""

class Solution:
    def int_to_roman(self, num):
        roman_map = [(1, 'I'), (4, 'IV'), (5, 'V'), (9, 'IX'), (10, 'X'),
                     (40, 'XL'), (50, 'L'), (90, 'XC'), (100, 'C'),
                     (400, 'CD'), (500, 'D'), (900, 'CM'), (1000, 'M')]
        result = ''
        next_level = len(roman_map) - 1
        while num != 0:
            roman = roman_map[next_level]
            if num >= roman[0]:
                result += roman[1] * (int(num / roman[0]))
                num = num % roman[0]
            next_level -= 1
        return result

if __name__ == '__main__':
    solution = Solution()
    assert 'III' == solution.int_to_roman(3)
    assert 'IV' == solution.int_to_roman(4)
    assert 'IX' == solution.int_to_roman(9)
    assert 'LVIII' == solution.int_to_roman(58)
    assert 'MCMXCIV' == solution.int_to_roman(1994)    
